802.11n Transmits to the New Wireless Standard

The wireless trend continues to flourish, and another era of new standards looms on the not-so-distant horizon. The most compelling and progressive is the emerging standard for 802.11n.

According to Alan Miano, product line manager, wireless, for small and medium business, 3Com, “802.11n is the next generation wireless standard.”

Many contractors have had great success on the installation side of the current wireless standards. 802.11a, 802.11b and 802.11g have all shown their worth in the real world, which explains why many have high hopes for 802.11n.

What’s the difference?

While many are still trying to understand the complete differences between the prior wireless standards, the next logical question centers around what will eventually be the main differentiator of 802.11n.

“The main difference between 802.11n and the previous standards is increased throughput and range,” Miano said. All of the prior versions of 802.11 (a, b and g) clocked in with data rates around 54 megabits (Mb) and 20-25 Mb of throughput. The 802.11n version will significantly increase throughput rates to around the 100 Mb mark, which increases throughput fivefold. The increase in speed also is accompanied by an increase in range of operation. Miano said the range increase should be around two to three times that of a, b and g.

One thing to keep in mind at this early stage of the game is that, right now, 802.11n is proposed, not ratified. Though it is expected to be ratified in early 2009, currently there is only the best vision of what it will be.

MIMO

One aspect of 802.11n that is both revolutionary and a distinctive difference is a technology called multiple input, multiple output (MIMO). It is a key difference between 802.11n and its predecessors. It is the technology that allows for the use of multiple transmitters coupled with multiple receivers. Also referred to as multipath, it is a way to reduce the problems incurred when only one transmitter and one receiver are used.

There is a matrix that helps determine the best setup. Depending on other factors, there could be two transmitters and two receivers, two transmitters and three receivers, or even three transmitters and three receivers. This is a big step in technology and helps achieve those higher throughput and range rates that 802.11n brings to the table.

“What happens is signals bounce off of everything, plants, people, walls,” Miano said. “This means that the signal has multiple reflections, and when it finally arrives at the receiver, it does not know which signal is the original one.” MIMO is a way to take that prior disadvantage and turn it into an advantage. The way that is done is through combining those signals to get one stronger signal.

Other benefits

802.11n also brings with it other benefits, such as spacial multiplexing, channel bonding and packet aggregation.

Spatial multiplexing occurs when a single data stream is broken down into multiple portions, which allow for the modified signal to be sent two to three times as fast. Then on the backend, back at the receiver, digital signal processing (DSP) technology is used to combine all of those smaller streams to make it one single data stream once again. This means more data can flow through the wireless transmission channel in a given time period by being split into multiple streams and transmitted simultaneously.

Channel bonding also is an important advancement with 802.11n. Channel bonding combines two adjacent 20 MHz channels into a single 40 MHz channel to effectively double the bandwidth and throughput.

Packet aggregation is a way to alleviate the problems incurred by packet header overhead that reduces data throuput. By combining packets to create a larger packet, one is able to send more data for a given amount of overhead.

What it all means

Miano said the four key differences of 802.11n (MIMO, spatial multiplexing, channel bonding and packet aggregation) all are advancements over prior 802.11 versions. He also pointed out that they need to keep in mind that 802.11n has not been officially ratified as a standard yet.

One thing he mentions, and something that contractors can start thinking about at this time, is that when they work with projects that might opt for 802.11n at some point, they need to be cognizant of the cabling requirements.

“If someone may want to deploy 802.11n, it should ring an alarm to contractors that 802.11n is best used with a gigabit connection and the cabling needs to be rated Cat 5e or higher,” Miano said. “If not, the wireless network will run faster than the wired one, and that is a design faux pas.”

Industry experts see the inevitable transition to 802.11n happening in the same manner as the transition to 802.11g in that it will most likely be driven initially by the consumer market. Because the products for the consumer space are less expensive, complete product replacement is easier and the requirement of formal standards is not relevant. The consumer space is almost perceived as the testing grounds for new technology like 802.11n.

Generally, once the consumer market implements such new technology, the enterprise space follows suit. Miano says that products are already being certified as 802.11n draft 2.0 compliant, and that is a nice step towards widespread adoption. However, until the standard is ratified, enterprise customers considering 802.11n should ensure products under consideration are certified as 802.11n Draft 2.0 compliant. The final ratification and approval for the 802.11n standard is right around the corner. That means contractors who work with wireless systems should start learning about 802.11n, so they can be ready for the eventual demand by business customers, from small to large enterprises.
STONG-MICHAS, a freelance writer, lives in central Pennsylvania. She can be reached at jennifer.stong@comcast.net.